Answer:
A. physical; sublimation
Explanation:
When dry ice turns directly into a gas, a physical change called sublimation occurs.
Sublimation is a physical transformation that consists of the direct passage of a substance from the solid state to the gaseous state and vice versa, without going through the liquid state. A clear example of Sublimation is in the form of dry ice, we can visualize the transition from the solid to the vapor state characterized by the dense smoke that exudes from this material.
The sublimation of dry ice occurs when the ambient pressure is not sufficient to prevent the atomic particles from evaporating immediately, and so the material does not pass through the liquid state and goes directly to the gas.
